What is the most effective approach for managing blood glucose levels using a sliding scale insulin regimen?

Sliding Scale Insulin in Hospitalized Patients

Sliding scale insulin (SSI) alone should not be used as the primary insulin regimen for hospitalized patients with diabetes, as it provides inferior glycemic control and higher rates of hyperglycemia compared to basal-bolus or basal-plus approaches. 1

When SSI Alone May Be Acceptable

SSI has very limited appropriate use in the hospital setting:

• Patients without pre-existing diabetes who have mild stress hyperglycemia may be managed with SSI alone 1, 2
• Patients with well-controlled diabetes (HbA1c <7%) on minimal home therapy who develop only mild hyperglycemia during hospitalization 2
• Patients who are NPO with no nutritional replacement and only mild hyperglycemia 2
• Patients who are new to steroids or tapering steroids 2

However, basal insulin should be added if glucose levels cannot be maintained below 180 mg/dL (10.0 mmol/L) with SSI alone. 1

Why SSI Alone Fails

The evidence against SSI as a standalone regimen is compelling:

• SSI treats hyperglycemia reactively rather than proactively, leading to rapid blood glucose fluctuations that worsen both hyper- and hypoglycemia 2
• Mean blood glucose levels are 14.8 mg/dL (0.8 mmol/L) higher with SSI compared to basal-bolus insulin (95% CI 7.8 to 21.8; P < 0.001) 3
• Only 12% of SSI injections successfully reduced elevated glucose to target range (90-130 mg/dL), while 84% of injections were subtherapeutic 4
• Glycemic control (mean glucose <140 mg/dL) was achieved in only 38% of patients on SSI versus 68% on basal-bolus insulin 2

Recommended Approaches Instead of SSI

For Type 2 Diabetes with Good Oral Intake: Basal-Bolus Regimen

Randomized trials consistently demonstrate superior glycemic control and reduced complications with basal-bolus insulin compared to SSI alone. 1

• Start with 0.3-0.5 units/kg total daily dose: 50% as basal insulin (once or twice daily) and 50% as rapid-acting prandial insulin (divided before three meals) 1, 2
• Use lower doses (0.3 units/kg) for high-risk patients: older adults (>65 years), those with renal failure, or poor oral intake 1
• Reduce total daily dose by 20% for patients on high home insulin doses (≥0.6 units/kg/day) to prevent hypoglycemia 1
• Add correction doses of rapid-acting insulin for pre-meal hyperglycemia 2

The basal-bolus approach reduces complications including postoperative wound infection, pneumonia, bacteremia, and acute renal and respiratory failure. 1

For Type 2 Diabetes with Poor Oral Intake or NPO: Basal-Plus Regimen

For patients with mild hyperglycemia, decreased oral intake, or undergoing surgery, a basal-plus approach is preferred over both SSI alone and full basal-bolus. 1

• Give 0.1-0.25 units/kg/day of basal insulin once daily 1, 2
• Add correction doses of rapid-acting insulin for hyperglycemia before meals or every 6 hours if NPO 1
• This approach balances efficacy with lower hypoglycemia risk compared to full basal-bolus 1

For Type 1 Diabetes: Never Use SSI Alone

SSI alone should never be used in patients with type 1 diabetes—this is dangerous and can lead to diabetic ketoacidosis. 1

• Type 1 diabetes requires basal insulin at all times to prevent ketosis 5
• Use approximately one-third of total daily insulin as basal insulin, with short-acting premeal insulin for the remainder 5

Critical Safety Considerations

Hypoglycemia Risk

While basal-bolus insulin provides better glycemic control, it carries 4-6 times higher risk of hypoglycemia compared to SSI (RR 5.75 for glucose ≤70 mg/dL; RR 4.21 for glucose ≤60 mg/dL). 1

• Mild hypoglycemia occurs in 12-30% of patients on basal-bolus in controlled settings 1
• In real-world practice, severe hypoglycemia may occur more frequently and can be life-threatening 1
• Patients with renal impairment, hepatic dysfunction, older age, or poor oral intake require lower insulin doses 1, 5

Common Pitfalls to Avoid

• Never continue the same SSI regimen throughout hospitalization without modification despite poor control 2, 4
• Avoid premixed insulin (70/30) in hospitals due to unacceptably high hypoglycemia rates 1
• Do not rely solely on correction doses—scheduled basal insulin is the foundation 2
• Ensure proper documentation: approximately 30% of insulin administration records have missing or uncertain information regarding timing, glucose levels, or doses 4

Monitoring and Adjustment

• Check blood glucose before meals and at bedtime 6
• If correction doses are frequently required, increase scheduled insulin doses accordingly 2
• Target conventional glucose range of 140-180 mg/dL for most hospitalized patients 2, 7
• Increase monitoring frequency in patients at higher risk for hypoglycemia or those with reduced symptomatic awareness 5